Group B streptococci (GBS) are a major cause of neonatal sepsis and meningitis. Early diagnosis of GBS infections in neonates would allow extensive therapeutic intervention with possible increases in survival rates. Using a commercial latex particle agglutination test, we detected GBS antigen in the amniotic fluid, gastric fluid and serum of rhesus monkey infants as early as 24 hours following bacterial challenge. Additional studies with our model have failed to demonstrate inhibitory factors in normal rhesus monkey amniotic fluid. Rhesus amniotic fluid is an excellent growth media for this bacteria. These findings in rhesus monkeys are in conflict with human studies in which the growth of GBS appears to be inhibited by normal amniotic fluid. Utilizing our rhesus model for perinatal GBS infection, we have been able to demonstrate the safety and efficacy of intravenous immunoglobulin to provide GBS specific IgG to newborn babies. This has prompted the use of intravenous immunoglobulin as a method of producing significant increases in GBS IgG in amniotic fluid which enhances bacterial opsonization and protection from neonatal disease.